1. Field of the Invention
The invention relates to an optical receiver which has a signal splitter.
2. Description of the Prior Art
Such optical receivers are known, for example, from "Lichtwellenleitertechnik" [Light Guide Technology] by Dieter Lutz, Publ. Pflaum Verlag Munchen, 1986, pp. 279 to 289.
The amplifiers contained in such prior art receivers are preferably so-called transimpedance amplifiers, since they are usable for signals with a broad bandwidth and a broad dynamic range. Such prior art receivers are disadvantageous for analog signal transmission since they have non-linearities and poor harmonic properties. However, such prior art transimpedance amplifiers are particularly suited for digital signal transmission because the requirements regarding linearity and harmonic properties are reduced for digital signals.
An alternative receiving concept for analog signal transmission is disclosed in European Patent Application No. 0 372 742 A2. This concept utilizes a photodiode, a transformer and an amplifier as the optical receiver for signals with a broad bandwidth up into the UHF range. The photodiode and the transformer are series-connected in European Patent Application 03 72742 A2.
In some transmitting systems, the simultaneous transmission of an analog signal with a wide bandwidth, for example having therein both a broadband cable TV signal, and a narrowband digital signal, is desired.
In the following paragraphs, an input signal from an input source will be referred to as a wideband signal. The wideband signal includes, for example, a cable TV signal which will be referred to hereinbelow as a broadband signal (and also hereinafter referred to as a BB signal), and a digital signal which will be referred to hereinbelow as a narrowband signal (and also hereinafter referred to as an SB signal). It is intended to transmit all these signals simultaneously over a common light guide.
An optical transmission system with an optical receiver and a signal splitter downstream of the optical receiver is known in principle from European Patent Application EP-A2-0 386,482 (which corresponds to Australian Patent No. 622,523 published on Oct. 9, 1992).
EP-A2-0 386,482 includes an optical receiver of a known type therein. An optical input signal of the optical receiver in EP-A2-0 386,482 is transformed into an electrical signal. The electrical signal, which contains TV and telephone signals, is split into its two signal components in a signal splitter connected downstream of the optical receiver.